CS 6910 – Pervasive Computing Spring 2007 Section 1 (Ch.1): Introduction to Wireless and Mobile...

CS 6910 – Pervasive ComputingSpring 2007

Section 1 (Ch.1):

Introduction toWireless and Mobile Systems

Prof. Leszek LilienDepartment of Computer Science

Western Michigan University

Slides based on publisher’s slides for 1st and 2nd edition of: Introduction to Wireless and Mobile Systems by Agrawal & Zeng© 2003, 2006, Dharma P. Agrawal and Qing-An Zeng. All rights

reserved.

Some original slides were modified by L. Lilien, who strived to make such modifications clearly visible. Some slides were added by L. Lilien, and are © 2006-2007 by Leszek T. Lilien. Requests to use L. Lilien’s slides for non-profit

purposes will be gladly granted upon a written request.

Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 2

Chapter 1

INTRODUCTION

[Image of 2nd ed. cover added by L. Lilien.]


Evolution Distributed Computing (DIST)

Originally wireline only Wireless Computing

Originally non-mobile wireless only Mobile Computing (MOBI)

Really: Wireless & Mobile Computing Pervasive Computing (PERV)

Note: Textbook uses “wireless” and “mobile” as synonyms

Not precise: e.g., can have wireless but not mobile

Q: Why to study Wireless & Mobile Computing?A: It is foundation for PERV, its critical technology &

building block Some other technologies for Pervasive Computing:

Embedded computing Sensornets Opportunistic networks (oppnets) and systems

See Lecture Section 0.B

© 2007 by Leszek T. Lilien

Pervasive vs. Wireless & Mobile Systems


1.1. The History of Mobile Radio Communication (1/3)

1880: Hertz – Initial demonstration of practical radio communication 1897: Marconi – Radio transmission to a tugboat over an 18 mi path 1921: Detroit Police Department: -- Police car radio dispatch (2 MHz

frequency band) 1933: FCC (Federal Communications Commission) – Authorized four

channels in the 30 to 40 MHz range 1938: FCC – Ruled for regular service 1946: Bell Telephone Laboratories – 152 MHz (Simplex) 1956: FCC – 450 MHz (Simplex) 1959: Bell Telephone Laboratories – Suggested 32 MHz band for high

capacity mobile radio communication 1964: FCC – 152 MHz (Full Duplex) 1964: Bell Telephone Laboratories – Active research at 800 MHz 1969: FCC – 450 MHz (Full Duplex) 1974: FCC – 40 MHz bandwidth allocation in the 800 to 900 MHz range 1981: FCC – Release of cellular land mobile phone service in the 40 MHz

bandwidth in the 800 to 900 MHz range for commercial operation

Emphasis (underlines) on this and next 2 slides added by LTL


The History of Mobile Radio Communication (2/3) 1981: AT&T and RCC (Radio Common Carrier) reach an agreement to

split 40 MHz spectrum into two 20 MHz bands. Band A belongs to nonwireline operators (RCC), and Band B belongs to wireline operators (telephone companies). Each market has two operators.

1982: AT&T is divested, and seven RBOCs (Regional Bell Operating Companies) are formed to manage the cellular operations

1982: MFJ (Modified Final Judgment) is issued by the government DOJ [LTL: Dept of Justice]. All the operators [LTL: RBOCs] were prohibited to (1)

operate long-distance business, (2) provide information services, and (3) do manufacturing business

1983: Ameritech system in operation in Chicago 1984: Most RBOC markets in operation 1986: FCC allocates 5 MHz in extended band 1987: FCC makes lottery on the small MSA [LTL: Metropolitan Statistical

Area] and all RSA [LTL: Rural Service Area] licenses 1988: TDMA (Time Division Multiple Access) voted as a digital cellular

standard in North America 1992: GSM (Groupe Speciale Mobile) operable in Germany D2 system


The History of Mobile Radio Communication (3/3) 1993: CDMA (Code Division Multiple Access) voted as another digital

cellular standard in North America 1994: American TDMA operable in Seattle, Washington 1994: PDC (Personal Digital Cellular) operable in Tokyo, Japan 1994: Two of six broadband PCS (Personal Communication Service) license

bands in auction 1995: CDMA operable in Hong Kong 1996: US Congress passes Telecommunication Reform Act Bill 1996: The auction money for six broadband PCS licensed bands (120 MHz)

almost reaches 20 billion US dollars 1997: Broadband CDMA considered as one of the third generation mobile

communication technologies for UMTS (Universal Mobile Telecommu-nication Systems)

During the UMTS workshop conference held in Korea 1999: ITU (International Telecommunication Union) decides the next

generation mobile communication systems (e.g., W-CDMA, cdma2000, etc.) 2001: W-CDMA commercial service beginning from October in Japan 2002: FCC approves additional frequency band for Ultra-Wideband (UWB)


[LTL:]

RF = radio frequency



Applications[LTL:] Wireless Telephone

Cincinnati, OH

Washington, DC

[LTL:] User moves but phone # unchanged

Maintaining the telephone number across geographical areas in a wireless and mobile system


1G - First Generation Primarily for voice communication Using FDM (frequency division multiplexing)

2G - Second Generation Emphasis still on voice communication but allows for… … Data communication Using TDM (time division multiplexing) Indoor/outdoor and vehicular environment

3G - Third Generation Integrated voice, data, and multimedia communication Need for:

High volume of traffic / Real time data communication Flexibility, incl.

Frequent Internet access Multimedia data transfer

Compatibility with 2G Using compression

Without compromising quality


Generations of Wireless Systems & Services


First Generation Wireless Systems and Services

1970s Developments of radio and computer technologies for 800/900 MHz mobile communications [1st mobile band]

1976 WARC (World Administrative Radio Conference) allocates spectrum for cellular radio

1979 NTT (Nippon Telephone & Telegraph) introduces the first cellular system in Japan

1981 NMT (Nordic Mobile Telephone) 900 system introduced by Ericsson Radio System AB and deployed in Scandinavia

1984 AMPS (Advanced Mobile Phone Service) [cellular] introduced by AT&T in North America

Emphasis (underlines) and text in square brackets on this and next slide added by LTL

Note: “Cellular systems” called “mobile systems” outside North America.


Second Generation Wireless Systems and Services1982 CEPT (Conference Europeenne des Post et Telecommunications)

established GSM [global special mobile] to define future Pan-European Cellular Radio Standards

1990 Interim Standard IS-54 (USDC [US digital cellular]) adopted by TIA (Telecommunications Industry Association)

1990 Interim Std IS-19B (NAMPS [narrowband AMPS]) adopted by TIA

1991 Japanese PDC (Personal Digital Cellular) system standardized by the MPT (Ministry of Posts and Telecommunications)

1992 Phase I GSM system is operational

1993 Interim Standard IS-95 (CDMA) adopted by TIA

1994 Interim Standard IS-136 adopted by TIA

1995 PCS Licenses [added 2nd band (1900 MHz)] issued in North America

1996 Phase II GSM operational

1997 North American PCS deploys GSM, IS-54, IS-95

1999 IS-54: in North AmericaIS-95: in North America, Hong Kong, Israel, Japan, China, etcGSM: in 110 countries


Basic technology in the U.S. cdma2000

Basic technology in Europe & Japan W-CDMA

Similar but design & implementation differences


Two Basic Technology Choices for 3G


Third Generation Wireless Systems and Services (1/2)

IMT-2000 (International Mobile Telecommunications-2000):

- Fulfill one's dream of anywhere, anytime communications a reality.

Key Features of IMT-2000 include:

- High degree of commonality of design worldwide;

- Compatibility of services within IMT-2000 and with the fixed networks;

- High quality;

- Small terminal for worldwide use;

- Worldwide roaming capability;

- Capability for multimedia applications, and a wide range of services and terminals.


Third Generation Wireless Systems and Services (2/2)

Important Component of IMT-2000 is ability to provide high bearer rate capabilities:

- 2 Mbps for fixed environment;- 384 Kbps for indoor/outdoor and pedestrian

environments;- 144 Kbps for vehicular environment.

Standardization Work:- Release 1999 specifications- In processing

Scheduled Service: - Started in October 2001 in Japan (W-CDMA)


Future: 4G 4G

Expected to implement all standards from 2G & 3G Infrastructure only packet-based, all-IP Some of the standards paving the way for 4G:

WiMax WiBro (Korean) 3GPP Long Term Evolution

To improves the UMTS mobile phone standard Work-in-progress technologies

E.g., HSOPA, a part of 3GPP Long Term Evolutionon



Subscriber Growth for Wireless Phones

3G Subscribers

2G Digital-only Subscribers

1G Analog-only Subscribers

Subs

crib

ers

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

Year


China Leads World in Mobile Phone Users

Total [World] Mobile Users > 800 million [2003] Total [World] Analogue Users > 70 million [2003]

ZDNet UK reports that the number of mobile phone users in China reached 167 million in April, 2002, a rise of 6 million subscribers on March, 2002.

The US, which is the second biggest market, has 136 million subscribers.

Mobile phones are the preferred mode of communication in Japan, with 56.8 million subscribers as of the end of March, 2003.


Many diverse subsystems Different requirements for different needs Different characteristics

Corresponding to the requirements Different coverage areas

Cell = area that can be covered by a single transmitting station (usually called base station) Picocells, microcells, macrocells & global “cell”

Figure – next slide

Why different cell sizes? Limited nr of channels per cell Smaller cells can serve more users

E.g. 2x smaller => can serve 2x more users on the same band (with smaller range)


Flexibility & Versatility of 3G


Coverage Aspect of Next Generation Mobile Communication Systems

Picocell Microcell Macrocell Global

Urban

Suburban

Global

Satellite

In-Building


Transmission Capacity as a Function of Mobility

Broadband radio

Glo

bal S

yste

m f

or M

obil

e C

omm

unic

atio

ns

0.01 0.1 1 10 100

Transmission capacity as a function of mobility in some radio access systems

Mob

ilit

y

Universal Mobile Telecommunica- tions System

Mobile Broadband System

Broadband Satellite Multimedia

Local Multipoint Distribution System

Satellite Universal Mo-bile Telecommunica- tions System

Data Rate (Mb/s)

Stationary

Pedestrian

Vehicular


1.2. Characteristics of Cellular SystemsWireless Technology & Associated Characteristics

Wireless Technologies Cellular WLAN (Wireless LAN) GPS Satellite Based PCS Campus network (e.g., Ricochet, Carnegie Mellon U.) Home Networking Ad Hoc Networks WPAN (Wireless PAN = [personal area network])

Incl. Bluetooth Sensor Networks

Different technologies needed for different applications

-- Details on the next slide –

[From 1st ed. slides – Slightly modified by LTL]


[LTL: Yellow and red highlights added]

(phone calls)

(CMU campus)

(also oppnets, IANs)

(WPAN = wireless personal area network)


Wireless Technologies for Application Classes

[LTL: Yellow and red highlights added]

Notice the following: Infrastructure-based networks vs. ad hoc networks

(p. 11/2)

Terms & acronyms: Access point – AP (p. 8/-1, 10/2) Mobile station – MS (p. 11/2) Handoff and switching radio resources (p. 11/3)


Application Example: Medical Application

Wireless remote consultation

ATM backbone network

ATM backbone network

Possibility for remote consulting(including audio visual communication)

ATM switch

ATM switch

Remote databases

In hospitalphysician

Ambulance


Wireless Features & Their Potential Apps

[LTL:] Notice the following (p. 11/-1):

“Anytime anywhere” not always required Often “many time” or “many where” is adeqate

Permanent connectivity not necessary MS can:

Start transaction at AP1, then move away (loosing connection to it) Get close to AP99 & complete transaction at AP99


1.3. Fundamentals of Cellular Systems

Illustration of a cell with a mobile station (MS) and a base station (BS)

BS

MS

Cell

Hexagonal cell area used in most models

Ideal cell area (2-10 km radius)

(circle)

Alterative shape of a cell

(square)

MS

[LTL:]

Cell shapes (above) Actually, cell may have a zigzag shape Hexagon is a good approximation in practice

Also, gives non-overlapping cells (used by clever bees for beehives)

E.g., circles would either overlap, or would have gaps in between


Single BS per cell =>limited bandwidth per cell

Increase bandwidth useefficiency by multiplexing

4 +1 basic multiplexing techniques FDMA – frequency division multiple access TDMA – time division multiple access CDMA – code division multiple access OFDM – orthogonal frequency division multiplexing New: SDMA – space division multiple access

Specialized for microwave antennas


Cell Bandwidth Limitations & Multiplexing

BS

Service area

(Zone)

MS

MS


FDMA (Frequency Division Multiple Access)

User 1

User 2

User n

…

Time

Frequency

[LTL:]

Used in all 1G cellular systems BS allocates to each of n users a channel (a

frequency subband) for time the user needs it


FDMA Bandwidth Structure

1 2 3 … nFrequency

Total bandwidth[LTL:] Divided into n channels

(frequency subbands)

4


FDMA Channel Allocation

Channel 1 User 1

Channel 2 User 2

Channel n User n

Base Station

… …

Mobile Stations


TDMA (Time Division Multiple Access)

Use

r 1

Use

r 2

Use

r n

…

Time

Frequency

[LTL:]

Used in most 2G cellular systems BS allocates to each user full bandwidth for

duration of a time slot


TDMA Frame Structure

1 2 3 … nTime

Frame

[LTL:] Divided into n time slots(by a round-robin method)

4


TDMA Frame Illustration for Multiple Users

Time 1

Time 2

Time n……

Base Station

User 1

User 2

User n

…

n Mobile Stations

[LTL:]

Note: Non-overlapping time slices “Time 2” slot starts after “Time 1” slot is over, etc.


CDMA a.k.a. spread spectrum technique Used in some 2G and most 3G cellular systems

Simultaneous transmission of data from multiple users on full frequency band Figure shows all users using:

Same range of frequencies Same time rangeBut Different codes

CDMA is enabled by orthogonalcodes (= keys) One distinct code assigned

by BS to each user


CDMA (Code Division Multiple Access)


CDMA transmission Transmitter:

Codes (using the key) each user’s data “stream” Puts all coded individual data “streams” on data link

Creates a common “mixed” data stream

Receiver: Gets common “mixed” data stream from data link Uses keys to decode (“unmix”) individual data stream

from the “mixed” data stream

# of simultaneous users limited by # of possible orthogonal codes

Complex but robust technique


CDMA (Code Division Multiple Access) – cont.


[SKIP:] Transmitted & Received Signalsin a CDMA System

Information bits

Code at transmitting end

Transmitted signal

Received signal

Code at receiving end

Decoded signal at the receiver

[LTL:] 10-bit codewords


Frequency Ranges used forFDMA, TDMA & CDMA


OFDM idea – to reduce interference Convert single high-speed data stream to multiple

low-speed data streams Low-speed data streams sent in parallel using

(sub)channels working on multiple-frequencies

Frequencies of subchannels in FDMA vs. OFDM FDMA – non-overlapping frequen-

cies of subchannels Even with gaps between subchannel

bands to reduce interference OFDM - overlapping frequencies

of subchannels


OFDM (Orthogonal Frequency Division Multiplexing)

Figure: Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng.

All rights reserved

39


Many variants & combinations of FDMA, TDMA & CDMA - beyond the scope of this discussion

Frequency hopping – combines FDMA & TDMA

Idea: One user uses one channel for a time slot, then changes to another channel for another time slot

See the next slide Receiver needs to know frequency hopping

sequence

Main advantage (e.g., in defense applications):Message gets through even if one frequency band jammed


Variants & Combinations ofFDMA, TDMA & CDMA


Frequency Hopping

Frequency

f5

f4

f3

f2

f1

Frame Slot

Time

[LTL:] Each user gets one time slot per frame, on a different frequency (round-robin used for frequency selection)


1.4. Cellular System Infrastructure

BS

Service area (Zone)

Early wireless system: Large zone

[LTL:]

Large zone requires a high-power BS Better: replace large zone with smaller hexagonal

zones (next slide)


Cellular System: Small Zone

BS BS

BS BS BS

BS BS

Service area

[LTL:]

BS covers much smaller area now Requires much less power (for a given area)


Various kinds of Mobile Stations (MSs) a.k.a. wireless devices

Cellphone, PDA, PalmPilot, laptop with WiFi card, …

MSs need connectivity on the move E.g., connectivity from BSs in the cells they visit

BS is a gateway to wired infrastructure

Typical support for MSs: Cellular infrastructure See next slide


Cellular System Infrastructure


Home phone

PSTN

MSC

BSC …

BS

…

…

MS

…

BS MS

BSC

BS MS

…

BS MS

BSC

BS MS

…

BS MS

BSC

BS MS

…

BS MS

MSC

MS, BS, BSC, MSC, and PSTN

[LTL:] Several BSs connected via wireline links to one BSC (BS

controller) Several BSCs connected via wireline links to one MSC (Mobile

Switching Center) Several MSCs interconnected via wireline links to PSTN (Public

Switched Telephone Network) and the ATM backbone

wired link


BS consists of Base Tranceiver System (BTS)

Includes tower & antenna BSC

Contains all associated electronics


BS Structure


MSC database for supporting MS mobility1) Home location register (HLR) for MS

Located at the “home MSC” for MS Where MS is registered, billed, etc.

Indicates current location of MS Could be within home MSC’s areaOR Could be in the area of any MSC in the world

2) Visitor location register (VLR) on each MSC Contains info on all MSs visiting area of this MSC

Incoming call scenario Based on the called #, incoming call for an MS is

directed to the HLR of the “home MSC” for this MS HLR redirects the call to MSC/BSC/BS where the MS is

now VLR of the “current MSC” has info on MS (one of visiting MSs)


MSC Database Supporting MS Mobility & Incoming Call Scenario


Control and Traffic Channels

Base Station

Forward

(downlin

k) contro

l channel

Mobile Station

Reverse (

uplink) c

ontrol c

hannel

Forward

(downlin

k) traff

ic channel

Reverse (

uplink) tr

affic

channel

Note: Forward/reverse in the U.S., downlink/uplink elsewhere

[LTL:]

4 simplex channels needed for control & traffic 2 control channels

Exchange control msgs Forward channel & reverse channel

2 traffic channels For data Forward channel & reverse channel


More on Control and Traffic Channels

[LTL:]

Traffic channels used for call duration => Large # of traffic channels on each BS

Handshake steps for call setup use control channels

Control channels used for short duration => Small # of control channels on each BS MSs compete for these few control channels

For call setup, etc.



Steps for a Call Setup from MS to BS

BS MS

1. Need to establish path

2. Frequency/time slot/code assigned

(FDMA/TDMA/CDMA)

3. Control information acknowledgement

4. Start communic. on assigned traffic channel

[LTL:]

Steps for a call setup from MS to BS - When MS initiates a call

Tim

e


Steps for a Call Setup from BS to MS

BS MS

2. Ready to establish a path

3. Use frequency / time slot / code

(FDMA/TDMA/CDMA)

4. Ready for communication

5. Start communic on assigned traffic channel

1. Call for MS # pending

[LTL:]

Steps for a call setup from BS to MS: When MS responds to a call (somebody calls MS)

Tim

e


A Simplified Wireless Communication System Representation

Information to be transmitted (Voice/Data)

Coding Modulator Transmitter

Information received

(Voice/Data)

Decoding Demodulator Receiver

Antenna

AntennaCarrier

Carrier

[LTL:]

The figure shows major steps in wireless communications Signal processing operations – beyond the lecture scope Lecture will concentrate on system aspects of wireless

data communication


1.5. Satellite Systems Application areas of satellite systems

Traditional Applications Weather satellite Radio and TV broadcasting Military satellites Navigation and localization (e.g., GPS)

Telecommunication Applications Global telephone connections Backbone for global network Connections for communication in remote places or

underdeveloped areas Global mobile communications


Basic Concepts & Terminology Only LOS communication is possible

LOS = line of sight Satellites further away from earth cover a wider area Satelites can emit one or more satellite beams

Satellites w.r.t. position over earth Geostationary Rotating around the earth

ES – earth station



History of Satellite Systems

50th anniversary of the space age on October 4, 2007


1.6. Network Architectures and Protocols

[LTL:] Protocol = basic set of rules followed to provide systematic signaling steps for information exchange Other protocols:

Diplomatic protocols, protocol to login, … [LTL:] We will cover later following protocol

reference models and protocols: Open Systems Interconnections (OSI) reference

model Transmission Control Protocol (TCP) (on top of IP)

Internet Protocol (IP) Internet Protocol Version 4 (IPv4) Internet Protocol Version 6 (IPv6) – work in progress Mobile IP (MIP)


1.7. Ad Hoc Network [LTL:] Ad hoc network (AHN) Def 1: AHN is a local network with wireless connections or

temporary plug-in connections, in which mobile or portable device are a part of the network only while they are in close proximity

Def 2: AHN is a collection of wireless MHs forming a temporary network without the aid of any centralized administration or standard support services regularly available on the wide area network (WAN) to which the hosts may normally be connected

Examples: AHN 1: Instructor’s and students’ computers can create an AHN

during lectures AHN 2: Oppnet used after an earthquake



1.7. MANET

Source

Destination

[LTL:] MANET = mobile ad hoc network - an autonomous system of mobile nodes, mobile hosts (MHs), or mobile stations (MSs) connected by wireless links

MSs of a MANET also serve as routers These routers are mobile Route messages from SRC to DEST - see Figure

Multihop routing Store-and-forward passing of info in P2P (peer-to-

peer) way


MANETs – cont.1

MANETs are highly dynamic All nodes, incl. routers, are mobile

=> topology highly dynamic, unpredictable Topology change due to MSs mobility made known

to (some) other nodes Types w.r.t. infrastructure support

Stand alone - no infrastructure support Limited infrastructure support

Some routers have access to a fixed infrastructure

E.g., access to Internet – like in oppnets E.g., stub network (SN) –

Stub network = a single LAN which never carries packets between two remote hosts; all traffic is to and/or from local hosts

Multiple routers on SN don't route to one another, they will only route a packet into SN (if it's destined for SN), and out from SN (if it originated on SN) [cf. “stub network“ in Wikipedia]


MANETs – cont.2

Location of MSs in a MANET: within buildings, highways, vehicles, on and within human bodies

MANET nodes equipped with a “radio”“Radio” = wireless transmitter & receiver (or: wireless transceiver) With antenna

Types of antennas: Omnidirectional Directional Steerable Any combination of these

Xmit/rcv parameters affect MANET topology at any given moment


Wireless Sensor Networks

Base Station

Antenna

SensorTarget

[LTL:] (Ad Hoc) Wireless Sensor Networks (WSNs) – a specia-lized subclass of AHNs Sensor(s) in each node in addition to processor and

radio Sensors sense/measure some physical characteristcs

Temperature, humidity, acceleration, pressure, toxicity, … Can be planted at random

Even thrown out of a speedingvehicle, even from a plane

Note: The plane in the Figureis BS & collects data. Anotherone could have droppedsensor nodes earlier

BS collects &aggregatessensed info

Example 1 (Fig):Sensing enemy’smoves


Example 2: Sensing a Cloud of Smoke


1.8. Wireless LAN and PAN

IEEE 802.11 = Wireless Local Area Network (WLAN) using the IEEE 802.11

HiperLAN is a European Standard Bluetooth nets are examples of Wireless Personal Area Networks

(WPAN)

End of Section 1 (Ch.1)

Date post:	19-Dec-2015
Category:	Documents
View:	213 times
Download:	1 times

CS 6910 – Pervasive Computing Spring 2007 Section 1 (Ch.1): Introduction to Wireless and Mobile...

Documents